In recent years, digital AV devices perform various types of processing such as downloading content via a network, and storing and playing back content. Mechanisms for protecting copyrights of content in such devices have therefore become important.
There is disclosure of technology for implementing security in a processor, as a method of realizing content copyright protection in a digital AV device. The following describes this technology.
A processor core includes a secure mode for performing license management, content decryption, etc., and a normal mode for performing normal processing, and the secure mode and normal mode are switched between each other as processing is performed. When the processor accesses a bus slave module having a secure resource, such as an external memory, the processor core sends, to a bus interface, a mode status signal indicating whether the processor core is operating in the secure or normal mode, and the bus interface attaches a mode indicated by the mode status signal to an access request for the bus slave module, as a secure attribute. Accordingly, the bus slave module judges the secure attribute, and permits access to the secure resource if the secure attribute indicates “secure”.
Patent document 1: Japanese Patent Application Publication No. 2002-202720